Rock drill



P. H. NAST Ojct. 10, 1950 ROCK DRILL 3 Sheets-Sheet 1 Filed Sept. 24, 1945 p904 H N667;

0a. 10, 1950 P, H, MA T 2,525,422

' ROCK DRILL Filed Sept. 24, 1945 3 Sheets-Sheet 2 P. H. NAST Oct. 10, 1950 ROCK DRILL Filed Sept; '24, 1945 3 Sheets-Sheet 3 I Mill/III],

Patented Oct. 10, 1950 ROCK DRILL Paul H. Nast, West Springfield, Mass., assignor to Chicago Pneumatic Tool Company, New York, N. Y., a, corporation of New Jersey Application-September 24, 1945, Serial No; 618,277

This invention relates to rock drill mechanisms of the drifter type and more particularly to a buffer arrangement therefor.

It is an object of the present invention to :provide a'rock drill mechanism with a buffer ar rangement to prevent sudden shock in stopping the drill motor at the end of its rearward travel.

Another object is to .prevent the rock drill feed nut from being locked against reversal of rotation on the next forward movement of the drill motor.

' For other objects and for a better understanding of the invention, reference may be had to the following detailed description taken in connection with accompanying drawings, in which:

1 Fig. 1 is a top plan view, partly in section, of a rock drill mechanism embodying the features cross-sectional views taken respectively along lines 5, 55, and l''l of'Fig.1 and looking forwardly.

Referring particularly to Figs. 1, 2 and 3, the rock drill mechanism or assembly generally comprises aguide shell it, having a cone l2 for attaching the shell to an suitable support and a stationary feed screw I3, and a, drill motor M carrying a drill steel it. On the rear end of the drill motor housing, there is stacked in order, a cylinder back plate H, a reduction gear housing 18 and a feed motor housing 19. These parts are secured to the drill motor housing by through-bolts 2! located respectively at opposite sides of the parts. On the rear of the feed motor housing :9 are drill and feed motor valveihandles 22, 23 adapted to respectively. operate-drill and feed motor control valveszd; 26 located in the feed motor housing 19 at opposite sides of. the feed motor rotor 27, Figs. 4, 5. e

Air enters the drill through a single air inlet nipple 28 on the reduction gear housing l8, and is directed through ports 29, 3! therein to the drill and feed motor control valves 24, 26. As viewed in Fig. 5, these valves are in their off positions so that the drill is notin operation.

1 Claim. (Q1. 255 -145) The feed motor control valve-26 is held in .any i one of several positions by a detent plunger 32 and a spring 33, retained in the feed motor housing by a spring plug 34. The plunger; 32 is limited in its axial movement by a pin 35 and a cooperating slot 36 in the plunger 32. This feed'motor controlvalve 26 has three large indentations a1, 38 and 39 which respectively retainthe-valve in the off, reverse and forward positions. 'Betweenthe indentations-3land 39 is a series of small indentations H which, when alignedwith the plunger 32, hold the valve 25 in partly openedforward positions so that the feed motor may be throttled on forward speed from zero to maximum; t

The feed motor rotor '21 has six milled slots ll-carrying radially-slidable blades 43, and is supported in two roller bearings 44, mounted respectively in feed motor front and 'rear'end plates d6, Al. A rotor liner 48 is disposed-between the end plates -46, :41 and its inner diameter is'eccentrically-bored to givethe rotor blades '43 an outward and inward sliding movement. This assemblaga-including rotor 2l, front and rear end plates '46, 41, and rotor liner as is retained in the feed motor housing against angular displacement by a dowel M, which projects at one end "into the gear housing H3. A

spring washer '52 holds the end plates, 41 and I the liner '48 tightly together toprevent any leak age of air therebetween. On'the forward end of the'rotor 21, and ex tending into" the" reduction gear housing 18, is a pinion 53 adapted to mesh with an idler gear 54 having areplaceable bushing '55 rotatable "on a pin 56. Idler gear'fili has "other gear' teeth '51 which'mesh with gear teeth 58 of a feed screw'nut' 59 on feed screw 13. This feed screw .nut is journalled between a bearing 6i on the gear housing "[8 and a bearing Men the cylinder back plate IT. The gear pin '56 is also supported on both the gear hOllSlllg i8 and back plate "ll.

Guideshell H has a front feedscrew-support 64, *Fig; l,' for supporting the'forward end of the feed screw l3, and a buffer spring case cover -85 for supporting the rear 'end thereof. The "drill motor '1 is slidable in guide-ways 55, Figs; 5, 6, '7. 'Arear handle 61 is connected to shell rods fiil' and 69 by 'nuts H. These rods extend the full length of 'the shell from the buffer spring case cover 65 and rear handle 61 to the front feed screw support 64. The rear end of the feed screw has six splines 13 that act askeys upon matching key wa'ys l4 irrthe' 'mitting the motor to stall before the axial thrust against the feed nut becomes excessive. The bufier arrangement thus prevents sudden shock in stopping the feed motor and the feed nut from being locked with a stop in such a manner as would prevent reversal of rotation of the feed motor.

The reduction gear housing I8 has an-o-il reservoir 18 in which the rotor pinion 53 and idler gears 54, 51 are enclosed. This reservoir is filled through a threaded hole closed by an oil plug 19, Fig. 4.

In assembling the drill and feed motors, the cylinder back plate I1 is first fitted upon the rear end of the drill motor housing I4, Fig. 3. A dowel pin 81 is passed through the cylinder back plate I1 and extended into the drill motor housing I4 whereby to prevent relative angular movement therebetween. The dowel pin BI also projects rearwardly from the cylinder back plate and is received by an opening 82 in the gear housing I8 as the latter is in turn stacked upon the back plate. The same dowel pin 8| thus prevents angular movement of the gear housing I8.

In turn, the feed motor housing I9, including its rotor parts, is stacked upon the ear'housing Is. Relative angular movement between the feed motor I9 and the gear housing I8'is prevented by the dowel pin 5|. It will now be apparent that by means of two dowel pins 5|. 8| the stacked parts are retained against relative rotation and held in angular ali nment with the cylinder I4. These same parts are retained against axial displacement by t e through-bolts 2| extending through lugs 83, 84 on the respective drill and feed motor housings I4, I9. 7

The drill motor throttle valve 24 is operated by the handle 22 and is held in its adjusted o itions by a detent plun er '88 urged upwardly b a spring 81 and retained n the e d motor ousing by a spring plug 88. This val-e 2 has four indentations 90. BI, 92, 93, Fig. '7, that coop rate with the plun er 86 to respectively retain the valve in off, light run, run, and low positions.

Water for the drill motor to settle dust resulting from the drilling operation enters the rear end of the feed motor housing I9 through a niople 94 from a hose 95, Fig. 4. The water upon entering the feed motor housing is received in a chamber 96. Fig. 3, from where it passes by way of a passage 91 to a threaded recess 98 adapted to be closed by a screw plug 99. A fluid delivery tube IOI is inserted through the a sembled parts by way Of the threaded recess 98 and is held in place by the screw plug 99. The tube IOI enters the drill motor and delivers water to the drill steel in the manner shown in the patent to Lear 2,177,391. A packing gland I02 in the cylinder back plate I1 prevents leakage of oil from the oil reservoir 18 along the tube IIJI and toward the drill motor I4. The plug 99 forces a flange I03 on the tube against a washer I04 that compresses sealing rubber I05 to prevent leakage of the water in the threaded recess. 98

to the feed motor. Any air pressure that may be built up within the feed motor housing I9 is vented through the air vent passage I06 to the atmosphere.

As the feed throttle valve handle 23 is turned upwardly, air is admitted to the feed motor blades. Air entering nipple 28 in the gear housing I8 passes through passage 3|, Fig. 1, central opening I01, radially-extending valve port I08, graduated groove I09, and finally as the valve is turned further, housing port IIO, liner groove I I I, circumferentially-spaced liner ports II2, to the spaces between rotor blades, Fig. 7. Rotor 21 is rotated clockwise driving idler gears 54-51 counter-clockwise and in turn feed screw nut 59 is driven clockwise on the stationary feed screw I3 to advance drill motor toward the work. The graduated groove I09 permits limited amounts of air to be supplied to the blades and its position can be altered to control the speed of the feed motor so that the feed motor may be adjusted to advance the drill motor at the same rate as the drilling speed.

At the same time that air is admitted to the blades to turn the rotor, air is passed to two housing holes I I4, Fig. 7, at the ends of the rotor liner 48. In registry with these holes II4 are front and rear end plate holes I I5, Fig. 5, directing air to segmental grooves H6 in the respective front and rear end plates 46, 41. As any of the six blade slots 42 register with the segmental plate groove II6, air is directed under the blades 43 to hold them out against the cocentric liner bore. For a more complete description and illustration of a conventional arrangement for directing live air from a segmental groove in the end plate to the inner edge ofthe blade, reference is made to Amtsberg Patent 2,037,358, April 14, 1936, and particularly to Fig. 11, thereof.

As the blades 43 pass liner exhaust holes II 1 registering with housing exhaust holes I I0 which lead into a main exhaust hole II 9,.the air betwe n the blades is exhausted to atmosphere. In addition to the liner exhaust holes II1, there are two exhaust holes I2I, Fig. 5, one in the front end plate and one in the rear end plate,

that also register with the housing holes II 8' thereby to increase the main exhaust capacity.

Such air as is ahead of the blades after they have passed the exhaust holes II1, I 2|, is exhausted through auxiliary exhaust port I22, Fig. 7. -The exhaust air leaves the blades through liner ports I23, linergroove I 24, housing port hole I25, circular exhaust groove I26 in the valve 26, Fig. 6, straight exhaust groove I21 in the valve 26, and circular exhaust groove I28 in the valve 26.

Any live air in the slots 42 under the blades 43 is exhausted into segmental grooves I3] and holes I32 in the front and rear end plates 46, 41, through the valve in the above manner and out auxiliary exhaust port I22.

When the feed motor throttle valve 26 is turned and plunger 32 is located in indentation 38 thereof, air is admitted to the feed motor housing through valve port I33, housing port I25, liner groove I 24, liner holes I23, and rotor 21 is caused .to rotate in a-counter-clockwise direction. The

passage I I9 to the atmosphere. The use of grooves I I6 and I3I in the end plates will be reversed. Air entering rotor slots 42 underneath blades 43 thus passes from grooves I3I and is exhausted to grooves I I6.

Operation of the drill motor I4 is the same as with the conventional drifter. The difference here is that the back head of the drill motor is eliminated and the special back plate I! is used. The usual air nipple, throttle valve, and water connections that are on the back head of the conventional drill motor are now in the present invention in the gear housing and feed motor housing.

A live air chamber I38 is provided in the cylinder back plate H to supply air to the distributing valve (not shown) in the drill motor. The drill motor may be constructed generally along the lines of the drill motor shown and described in the above-mentioned patent to Lear 2,177,391. Emergency blow holes I37, Fig. 3, I38, I39, Figs. 5, 6, for the drill motor, are also provided in the cylinder back plate I'I. When the drill motor throttle valve 24 is turned to the left and toward the running position, a valve port hole I4I registers with a passage I42 in the parts, Fig. 5, that connects with the drill motor supply chamber I36 in the cylinder back plate I'I. Live air in a valve central hole I43 coming from the air in the nipple 28 by wa of the passage 29 in the gear housing I8, is thus directed to the drill motor supply chamber I36 causing the drill motor automatic valve to operate.

When the plunger 86 is in the valve indentation 9|, Fig. 7, so that holes MI and I42 are only partially registered with each other only a limited amount of air is allowed to pass thereby, the drill motor will be run at a retarded speed. When plunger 96 is in indentation 92 the valve 24 is held so that holes MI and I42 are full registered and the drill motor runs at full speed.

When the plunger 86 is in the indentation 93, the throttle valve is in the emergency blow position. Valve port hole I46 registers with a housing passage I41 and supplies air to cylinder back plate port I37 by way of a passage I48 extending through the parts, Figs. 3, 5. Also, air will pass to blow holes I38, I39. Live air leaves central valve passage I43 and passes through valve port hole I5I, Fig. 6, valve groove I52, which will be in register with passage I53, and enters the holes I38, 139.

It should now be apparent that a built-in feed movement of the drill motor to prevent sudden shock in stopping the feed motor at high speed.

While various changes may be made in the detail construction of this rock drill mechanism, it shall be understood that such changes shall be within the spirit and scope of the present invention as defined by the appended claim.

What is claimed is:

In a rock drill mechanism, a guide shell, a stationary feed screw having an unthreaded portion, a feed screw nut rotatable on the feed screw, buffer means at the rear of the guide shell comprising a casing having a central longitudinal aperture, a cover for the casing disposed in the rear thereof, an annular flange on the casing projecting into the central aperture, a sleeve member mounted on the unthreaded portion of the feed screw and disposed within the aperture of the casing, an annular external flange on the sleeve to cooperate with the casing flange to prevent axial movement of the sleeve in one direction, compression spring means arranged between the casing, the cover, and the sleeve whereby to prevent sudden shock of the moving parts upon the rearward terminal movement of the feed screw nut.

PAUL H. NAST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,586,954 Templeton June 1, 1926 2,037,358 Amtsberg Apr. 14, 1936 2,115,231 Pearson Apr. 26, 1938 2,177,391 Lear Oct. 24, 1939 2,208,751 Dicker, Sr. July 23, 1940 2,221,118 Smith, Jr. et a1. Nov. 12, 1940 2,316,192 Sinclair Apr. 13, 1943 

